Inheritance
- 1. Inheritance •Autosomal Recessive Gene •Two Carriers required •Not on sex chromosome •1 : 2 : 1 Ratio
- 2. Continued… Table 1: Genes linked to Usher syndrome • Usher Type 1 Type Frequency Gene locus Gene Protein Function – USH1B – USH1G USH1B 39–55% 11q13.5 MYO7A Myosin VIIA Motor Protein • Usher Type 2 PDZ-domain USH1C 6–7% 11p15.1-p14 USH1C Harmonin protein – USH2A, USH2C, USH2D USH1D 19–35% 10q21-q22 CDH23 Cadherin 23 Cell adhesion • Usher Type 3 USH1E rare 21q21 ? ? ? – USH3A USH1F 11–19% 10q11.2-q21 PCDH15 Protocadherin 15 Cell adhesion USH1G 7% 17q24-q25 USH1G SANS Scaffold protein • USH1A and USH2B USH2A 80% 1q41 USH2A Usherin Transmembrane linkage – USH1A does not exist USH2C 15% 5q14.3-q21.1 GPR98 VLGR1b Very large GPCR – USH2B not verified PDZ-domain USH2D 5% 9q32-q34 DFNB31 Whirlin protein Synaptic USH3A 100% 3q21-q25 CLRN1 Clarin-1 shaping Several genes have been associated with Usher Syndrome using linkage analysis and DNA sequencing of the identified loci. A mutation in any one of these genes is likely to result in Usher Syndrome.